Apparatus for forming chain-links

ABSTRACT

Apparatus for forming chain links with minimum stress on the forming mandrel and dies in which a rod to be bent into a chain link of succeeding links of a chain is oriented into a longitudinal groove of a fixed mandrel by a feeder; a rod holder engages the rod medially while a pair of flanking dies engage the rod at one side move it toward the holder and form the back-curve (or initiate a portion of it) as the dies are moved in one direction; the flanking dies then move in an opposite direction simultaneously with the work holder, completing the back curve, where after the flanking dies move a distance substantially equal to the arc of the side curves being formed (corresponding to the outer configuration of the fixed mandrel) to form the rod into a substantial U-shape whereafter terminal ends of the rod are bent toward each other to complete the link.

United States Patent [191 Rahn [ May 21, 1974 1 1 APPARATUS FOR FORMING CHAIN-LINKS [75] Inventor:

[73] Assignee: Meyer, Roth & Pastor Maschinenfabrik Gmbl-l, Cologne, Germany I 22 Filed: Aug. 23, 1972 21 Appl; No.: 282,955

Paul Rahn, Cologne, Germany Primary Examiner-Charles W. Lunham Assistant Examiner-James R. Duzan Attorney, Agent, or Firm-Holman 8L Stern 5 7 ABSTRACT Apparatus for forming chain links with minimum stress on the forming mandrel and dies in which a rod to be bent into a chain link of succeeding links of a chain is oriented into a longitudinal groove of a fixed mandrel by a feeder; a rod holder engages the rod medially while a pair of flanking dies engage the rod at one side move it toward the holder and form the backcurve (or initiate a portion of it) as the dies are moved in one direction; the flanking dies then move in an opposite direction simultaneously with the work holder, completing the back curve, where after the flanking dies move a distance substantially equal to the arc of the side curves being formed (corresponding to the outer configuration of the fixed mandrel) to form the rod into a substantial U-shape whereafter terminal 5 Claims, 2 Drawing Figures FIG] PATENTED m 2 1 1974 APPARATUS FOR FORMING CHAIN-LINKS PRIOR ART, GENERALLY The instant invention concerns apparatus for forming chain links, the apparatus is provided with a fixed forming-mandrel which conforms with the inside-shape of the link being formed and is provided with a recess for receiving the chain link. Prior art devices are also provided with a feeder-guide for moving a rod tangentially into a mandrel; these devices are also provided with holder means which pressthe rodmedially against the mandrel and have, in addition, two forming dies which grip the rod-ends, and are movable tangentially to the mandrel at a 90 angle.

The forming of chain links made by means of such prior art devices is accomplished by first orienting the center of the rod in front of the mandrel; the holder presses the rod into a recess on the mandrel inorder to form the rear curve on the finished link, the curvatureforming dies contact the rod-ends from the opposite side of the mandrel and bend these ends around the mandrel; the holder means maintains the rear-curveforming of the rod; and finally, after the p're-forrning of the chain link into a U-shaped form, the curvatureforming dies are either guided alternately laterally, to complete the forming of the link, or this working phase is accomplished'by special side-forming dies; see the US. Pat. to Wattler, No. 3,431,723, for example.

The prior art has a disadvantage in that excessive stress is placed on the forming mandrel, the crosssection of which is substantially weakened by the portion receiving the preceding and previously formed chain link, in as much as the curved link back, formed by the center area of the rod, is comparatively short and as a result thereof the force for the moving force forming the height of back into the respective groove of the fixed mandrel is accordingly relatively high; this force requirement, however,'weakens further the remaining cross section ofthe mandrel. For this reason, breaks in the forming mandrel develope, even though a high-grade alloy is used to form the mandrel.

FIELD OF THE INVENTION It is the object of the instant invention to overcome the disadvantages of the prior art. This is achieved in the instant invention by the arrangement of two rear curve-forming dies which are positioned oppositeto the stress-movement of the holder means (and therewith to the forming movement of the forming-dies) and which are movable towards the rod-ends; as well as a holder device which is concurrently moved forward by the length of the arc of the back curvature previously formed.

The mandrel in the improvement is no longer stressed by the shaping of the back curvature of the chain link and the pressure-stresses on the holder means are substantially reduced and minimized, since the forming is made under full utilization of the entire rod length over the back-forming dies of the invention. Breaking of the mandrel is therefore reduced or eliminated; and the holder means may be constructed lighter and the means for moving the dies does not have to impose as much force and can be lesser. It is hereby however required, as mentioned above, that the holder means serves initially as an abutment for the rod during the shaping of the back-curvature, andthen, after this back-curvature is achieved, said holder means presses the rod with its now-formed curvature into the respective recess of the mandrel and retains it there for subsequent reverse curvature-forming procedures.

The instant invention may be simplified in that the back-forming portions are fixedly connected with the curvature forming dies and are activated by a mutual, positive working gear, whereby in the starting position, the back-forming dies must be positioned on the mandrel-sides and the forward curvature-forming dies must be positioned away from the mandrel for the rod. Both parts are then simultaneously guided, first from the mandrel-side towards the rod, in order to form the back-curve, and they are then moved in the opposite direction after the holder means has pressed the preformed rod against the mandrel, so that the dies bend the link into a U-shaped form.

This affords a further improvement in that combined holder means for forming-dies are utilized as the forward curvature-bending dies as well as for the backforming dies, whereby the die-holder means are provided with side plates parallel to the link-plane, which accept in a single die, the feeder-guide, and in the other instance mounts-an abutment for the rod, and in both cases, receives the rod-endstherebetween. The side plates carry, at their ends, the curvature-forming elements, for example,and preferably form-rolls, while the back-forming dies, for this reason, protrude between the side plates towards the rod-ends.

It is also possibleto insert the back-forming die ,into a windowshaped recess in one of the two side plates of each forming-die holder, and possible to incorporate the forming-die holder-shaft itself, utilizing therefore, forexample, a clamping-cap.

The instant invention is schematically illustrated by means of an exemplary embodiment .in the drawing, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic top plan view; and

FIG. 2 is a front elevational view of FIG. 1, looking towards the improved invention, with intermediate parts removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT A straight rod 5' is oriented in front of a mandrel 7 by means of a feeder-guide 6; (from left to right); the mandrel being provided with a recess 8, for receiving a preceding chain link 9, as well as with a transverse or longitudinal (normal to recess 8) groove 10, for receiving the pre-cut, straight rods. The rod in its straight form is retained on the mandrel 7 by means of a holder 11 which also serves as an abutment. According to the instant invention, two special forming-die holder means 12 are provided, which extend at their free ends, each, in two side plates 13. As shown in FIG. 2, these side plates 13 include on one hand the feeder-guide 6, on the otherhand an abutment pin 14 for the rod, and serve as support for forming-rolls 15 which are located at one side of the rod 5. The forming-die holder means 12 are provided with window like recesses 16 into which the back-forming dies 17 are insertable. These have apexes or terminal ends 18 which protrude from the bottom 19 of the recesses, between the side-plates on the mandrel-side, extending towards the ends of rods 5 arid engage the same during back-forming.

3 These dies are held in their position by spring or resilient caps 20 which are indicated by a broken line, and

they support themselves with their under-surface 21 OPERATION The bending operation is as follows:

In the starting position shown in FIG. 1, the rod 5 is pushed laterally from the feeder-guide 6 towards and into engagement with the abutment pin the forming-die holder-means 12 are moved into the first direction of the arrows 22 and the rod is thereby first bent at the rear into the form 23 indicated by the dotted lines such portions 18 engage the ends of workpiece 5 and bend them about holder 11 to form a back curve (23) when members 12 are moved in direction 22. Thereafter, the forming-die holder-means 12 move back into the direction of the arrows 24. The holder l1 simultaneously moves in the same direction according to arrow 25 up to the fixed abutment 7 and the pre-bent workpiece 23 (with the back curve) is formed according to the curvature at the sides of the mandrel 7; the

die holders 12 continue their movement in the direction ofthe arrow 24 and bend the rod 23 into a U- shaped form 26, also, as shown by the dotted lines-The final forming of the fully-extended U-shaped link-form is made then either by the lateral inward movement of the die-holders l2 alternatively from one side and then from the other side, .or by displacing of the die-holders outwardly and by pushing forward a special sideforming die; the latter being known in the art or in any suitable manner;

-What is claimed is: I I 7 Lin apparatus for forming successive links ofa chain of connected links comprising, in combination:

fixed forming mandrel means having an outer peripheral shape substantially conforming to the inner configuration of a chain link being formed, said mandrel means having one face including a recess portion for receiving a portion'of a previouslyformed chain link through which a successive link will be connected and formed;

' straight-rod feeder means at one side of said mandrel means for moving a straight workpiece rod into confronting relation to saidone'face;

abutment means at an opposite side of said mandrel means forengaging the workpiece and orienting it relative to 'said one face of the mandrel means in a position to be shaped thereabout, the improvement I in which:

said fixed mandrel means includes a longitudinal groove portion for receiving a complimentary medial portion of the straight workpiece rod therein;

a pair'of curvature-forming dies mounted for reciprocating movement at opposite sides of the mandrel means relative to the longitudinal groove portion in which a straight workpiece is disposed,

said curvature-forming diesincluding plural means for engaging terminal ends of the straight workpiece during successive reciprocatory movements; and

work holder means comprising a member for relative reciprocating movement relative tosaid mandrel means and including an abutment portion confronting said one face of the mandrel means in alignment with the longitudinal groove portion for engaging a workpiece disposed therein at a central portion of the workpiece and about which a bend can be made;

one said curvature-forming die means being mounted for movement in one direction in flanking relation to said workhholder means for forming on the holder means portion confronting the oneface a first bend in the workpiece by bending the work- .piece against said work holder means abutment portion, said work holder abutment portion being mounted for movement toward said longitudinal groove portion for retaining the workpiece, after the first bend has been formed, in said longitudinal groove portion,

another of said curvature forming die means being mounted for a second movement beyond said one face and the fixed mandrel for forming second bends in the workpiece ends to form a U-shaped configuration to the workpiece whereby the terminal ends of the U-shaped workpiece can be subsequently bent around the fixed mandrel at the face of the mandrel opposite said one face and complete the link. I

2. The apparatus as claimed in claim 1 in which said curvature-forming dies include pairs of spaced plate portions having a spacevin which the terminal endof the straight workpiece is received, said feeder means being positionable between the spaced plates of one of the curvature-forming dies and said abutment means being-positionable between the spaced plates of said other curvature-formingdie.

3. The apparatus as claimed in claim 1 in which sai means of said curvature-forming dies for engaging-the terminal ends of the workpiece comprise peripherallygrooved roller elements mounted on an axis of rotation normalto the longitudinal groove portion in the one face of said fixed mandrel 'means. I

4. The apparatus as'claimed in claim 1 in which said means of said curvature forming dies for engaging the terminal ends of the workpiece to form the first bend comprise terminal abutment portions on the curvatureforming dies for engaging the terminal ends of the workpiece when the forming dies are moved beyond the one face of the fixed mandrel into flanking relation v to the work holder means.

5. The apparatus as claimed in claim 4 in which said means of said curvature-forming dies for engaging the terminal ends of the workpiece comprise peripherallygrooved roller elements mounted on an axis of rotation normal to the longitudinal groove portion in the one face of said fixed mandrel means. 

1. In apparatus for forming successive links of a chain of connected links comprising, in combination: fixed forming mandrel means having an outer peripheral shape substantially conforming to the inner configuration of a chain link being formed, said mandrel means having one face including a recess portion for receiving a portion of a previously-formed chain link through which a successive link will be connected and formed; straight-rod feeder means at one side of said mandrel means for moving a straight workpiece rod into confronting relation to said one face; abutment means at an opposite side of said mandrel means for engaging the workpiece and orienting it relative to said one face of the mandrel means in a position to be shaped thereabout, the improvement in which: said fixed mandrel means includes a longitudinal groove portion for receiving a complimentary medial portion of the straight workpiece rod therein; a pair of curvature-forming dies mounted for reciprocating movement at opposite sides of the mandrel means relative to the longitudinal groove portion in which a straight workpiece is disposed, said curvature-forming dies including plural means for engaging terminal ends of the straight workpiece during successive reciprocatory movements; and work holder means comprising a member for relative reciprocating movement relative to said mandrel means and including an abutment portion confronting said one face of the mandrel means in alignment with the longitudinal groove portion for engaging a workpiece disposed therein at a central portion of the workpiece and about which a bend can be made; one said curvature-forming die means being mounted for movement in one direction in flanking relation to said workhholder means for forming on the holder means portion confronting the one face a first bend in the workpiece by bending the workpiece against said work holder means abutment portion, said work holder abutment portion being mounted for movement toward said longitudinal groove portion for retaining the workpiece, after the first bend has been formed, in said longitudinal groove portion, another of said curvature forming die means being mounted for a second movement beyond said one face and the fixed mandrel for forming second bends in the workpiece ends to form a U-shaped configuration to the workpiece whereby the terminal ends of the U-shaped workpiece can Be subsequently bent around the fixed mandrel at the face of the mandrel opposite said one face and complete the link.
 2. The apparatus as claimed in claim 1 in which said curvature-forming dies include pairs of spaced plate portions having a space in which the terminal end of the straight workpiece is received, said feeder means being positionable between the spaced plates of one of the curvature-forming dies and said abutment means being positionable between the spaced plates of said other curvature-forming die.
 3. The apparatus as claimed in claim 1 in which said means of said curvature-forming dies for engaging the terminal ends of the workpiece comprise peripherally-grooved roller elements mounted on an axis of rotation normal to the longitudinal groove portion in the one face of said fixed mandrel means.
 4. The apparatus as claimed in claim 1 in which said means of said curvature forming dies for engaging the terminal ends of the workpiece to form the first bend comprise terminal abutment portions on the curvature-forming dies for engaging the terminal ends of the workpiece when the forming dies are moved beyond the one face of the fixed mandrel into flanking relation to the work holder means.
 5. The apparatus as claimed in claim 4 in which said means of said curvature-forming dies for engaging the terminal ends of the workpiece comprise peripherally-grooved roller elements mounted on an axis of rotation normal to the longitudinal groove portion in the one face of said fixed mandrel means. 